Refrigerator having a cooler mounted in each of a refrigerator compartment and a freezer compartment

ABSTRACT

A refrigerator has a refrigerator compartment, a freezer compartment, and a low-temperature storage chamber formed in the refrigerator compartment and having a temperature lower than that of the refrigerator compartment. The refrigerator includes a compressor, a condenser, a first throttling device, a channel control valve, a refrigerator cooling unit, and a freezer cooling unit connected in series to form a refrigerating cycle. The refrigerator cooling unit and the freezer cooling unit are accommodated in the refrigerator compartment and the freezer compartment, respectively. The refrigerator also includes a second throttling device connected in parallel with the refrigerator cooling unit, a first air fan for sending cold air heat-exchanged by the refrigerator cooling unit to the refrigerator compartment, a second air fan for sending cold air heat-exchanged by the freezer cooling unit to the freezer compartment, a suction duct for introducing air inside the refrigerator compartment to the refrigerator cooling unit, a discharge duct for introducing air cooled by the refrigerator cooling unit into the refrigerator compartment and into the low-temperature storage chamber, and an electrically-operated damper accommodated in the discharge damper. When the electrically-operated damper is opened, an amount of air to be introduced into the low-temperature storage chamber is greater than an amount of air to be introduced into the refrigerator compartment.

TECHNICAL FIELD

The present invention relates to a refrigerator having a cooler mountedin each of a refrigerator compartment and a freezer compartment and,more particularly, to a refrigerator capable of improving the coolingperformance and reliability of a cooling system for the independentcooling of a freezer compartment and a refrigerator compartment.

BACKGROUND ART

Japanese Laid-Open Patent Publication (unexamined) No. 8-240373discloses a conventional refrigerator as shown in FIG. 1, which includesa refrigerator body 1 having a refrigerator compartment 2 and a freezercompartment 3 both defined therein for storing foods. The refrigeratorcompartment 2 and the freezer compartment 3 are partitioned by agenerally horizontally extending medial wall member 30 and are openedand closed by doors 4 and 5, respectively, hingedly mounted on a frontsurface of the refrigerator body 1.

A freezer cooling unit 8 is disposed on the rear side of the freezercompartment 3 for cooling air drawn from the freezer compartment 3 usingthe latent heat of evaporation of refrigerant. An air fan 7 connected toa rotary shaft of a fan motor 31 is disposed above the freezer coolingunit 8 for circulating into the freezer compartment 3 cold airheat-exchanged by the freezer cooling unit 8.

A plurality of shelves 32, on which foods are placed, are accommodatedwithin the refrigerator compartment 2 to partition it into a pluralityof small compartments. A low-temperature storage chamber 33, in whichspecific foods are stored at a specific temperature range, is defined atan upper portion of the refrigerator compartment 2, while a vegetablestorage chamber or crisper 6 is defined at a lower portion of therefrigerator compartment 2. A compressor 11 is disposed in a machinechamber positioned below the vegetable storage chamber 6.

A cold air discharging means 34 is provided on the rear side of therefrigerator compartment 2, while a duct member 36 having cold airoutlets 35 defined therein is provided on the rear side of thelow-temperature storage chamber 33. A refrigerator cooling unit 10 isdisposed on the rear side of the duct member 36 for heat-exchanging airdrawn through an air passage 37, while an air fan 9 connected to arotary shaft of a fan motor 39 is disposed above the refrigeratorcooling unit 10 so that the air drawn through the air passage 37 may beheat-exchanged by the refrigerator cooling unit 10 and introduced intothe refrigerator compartment 2 and the low-temperature storage chamber33 through cold air outlets 38 and through the cold air outlets 35,respectively.

The cold air discharging means 34 communicates at an upper portionthereof with a lower portion of the duct member 36 and extendsdownwardly to a rear portion of the vegetable storage chamber 6.

In the above-described conventional construction, however, thetemperature within the low-temperature storage chamber 33 depends on thedistribution ratio of air discharged from the cold air outlets 35 and38. Accordingly, when the heat load in the refrigerator compartment 2 islow, for example, when the temperature of the open air is low, theworking efficiency of the air fan 9 becomes low, making it impossible tocool the low-temperature storage chamber 33 down to a set temperature.Furthermore, if the low-temperature storage chamber 33 is cooled down tothe set temperature, the temperature within the refrigerator compartment2 becomes lower than a set temperature, thus causing a problem of havingto heat the refrigerator compartment 2 by the use of, for example, aheater.

In addition, even after the air fan 9 has stopped upon completion of thecooling of the refrigerator compartment 2, the cooling of the freezercompartment 3 continues and, hence, air in the proximity of therefrigerator cooling unit 10 is cooled by a refrigerant flowing throughthe refrigerator cooling unit 10. Because the cooled air flowsdownwardly from the refrigerator cooling unit 10 by convection, the coldair flows from the cold air outlets 38 into a lower portion of therefrigerator compartment 2, thus causing a problem of lowering thetemperature of the lower portion of the refrigerator compartment 2 belowa set temperature.

Japanese Utility Model Publication (examined) No. 58-35979 disclosesanother conventional refrigerator employing a refrigerating cycle asshown in FIG. 2.

In FIG. 2, 41 is a compressor, 42 a condenser, 43 a first capillaryserving as a means to reduce pressure, 44 a first evaporator for coolinga refrigerator compartment, 45 a second evaporator for cooling a freezercompartment, and 46 a channel control valve. 47 is a second (bypass)capillary connecting a flow-dividing portion 48 positioned between thefirst capillary 43 and the channel control valve 46 with a flow-mergingportion 49 positioned between the first evaporator 44 and the secondevaporator 45. 50 is a third capillary provided between the channelcontrol valve 46 and the first evaporator 44.

Thus, the refrigerating cycle is repeatedly started and stopped in orderto cool a freezer compartment and a refrigerator compartment (not shown)and to maintain them at comparatively low temperatures.

During the operation of the refrigerating cycle, a refrigerantcompressed by the compressor 41 is condensed and liquefied in thecondenser 42. When the channel control valve 46 is opened, the condensedrefrigerant, whose pressure is lowered by the first capillary 43,reaches the flow-dividing portion 48 in a medium-pressure state. Therefrigerant is then divided at the flow-dividing portion 48 to flowthrough the second capillary 47 and the third capillary 50.

Part of the refrigerant is reduced in pressure by the third capillary50, vaporized or gasified by the first evaporator 44 and the secondevaporator 45, and reabsorbed by the compressor 41. The other part isreduced in pressure by the second capillary 47, merged at theflow-merging portion 49, and vaporized or gasified by the secondevaporator 45.

The third capillary 50 has a much lower resistance than does the secondcapillary 47 and, hence, most of the refrigerant passes through thethird capillary 50 when the channel control valve 46 is open.

In addition, when the channel control valve 46 is in a closed state, thecondensed refrigerant is reduced in pressure by the first capillary 43and the second capillary 47, vaporized or gasified by the secondevaporator 45, and absorbed by the compressor 41.

The interior of the refrigerator is cooled by heat exchange with theevaporators whose temperature is lower in comparison with thetemperature inside the refrigerator.

In such a refrigerator, however, the refrigerant whose pressure has beenlowered by the first capillary 43 during the opening of the channelcontrol valve 46 is temporarily expanded when divided at theflow-dividing portion 48, and is then readmitted into the comparativelynarrow capillaries.

The refrigerant at the flow-dividing portion 48 is a two-phaserefrigerant composed of a gas and a liquid. Because the refrigeratorexperiences wide-ranging load variations due to changes in thetemperature of outside air, the opening and closing of the door, theintroduction and removal of food products, and the like, the flow ratein the capillaries also varies, changing the dryness of the refrigerantat the flow-dividing portion 48.

Because the flow rate in a capillary decreases when the gas phase of therefrigerant enters an inlet portion thereof, the flow rate of the thirdcapillary 50, which normally allows essentially all of the refrigerantto pass through, sometimes decreases and the flow rate through thesecond capillary 47 increases when a difference in resistance arisesbetween the second capillary 47 and the third capillary 50; for example,when one of them is filled with a liquid and the other is in a state inwhich a gas enters the inlet portion. The same applies to thetransitional period of opening or closing the channel control valve 46due to the changes in the inlet state of the capillaries.

A disadvantage is that due to such flow rate variations, the flow rateof the refrigerant through the first evaporator 44, which is used forthe cooling of the refrigerator compartment, is insufficient when suchcooling is needed, and the refrigerator compartment is not cooledproperly.

Another disadvantage is that because the heat capacity from theflow-dividing portion 48 to the channel control valve 46 iscomparatively high, these portions are heated by the ambient temperaturewhen the compressor 41 is stopped, dryness is enhanced during operation,the flow rate into the comparatively narrow capillaries decreases, andthe cooling performance is adversely affected.

In addition, the medium pressure of the flow-dividing portion 48 is sethigh in comparison with the vaporization pressure of the evaporator inorder to reduce the frosting of the channel control valve 46, so thethird capillary 50 must have a predetermined resistance value(resistance value close to the first capillary 43), and the secondcapillary 47 must have an even higher resistance value in order todivide the flow when the channel control valve 46 is open. Furthermore,the total resistance value of the capillaries is such that a seriesconnection is established between the first capillary 43 and the secondcapillary 47 when the channel control valve 46 is closed, and acombination of a series connection with the first capillary 43 and aparallel connection between the third capillary 50 and the secondcapillary 47 is formed when the channel control valve 46 is opened.

Since resistance is lower for a parallel connection than for eachindividual element, the difference in the overall resistance of therefrigerating cycle between the open and closed states of the channelcontrol valve 46 is extremely large. The reduced-pressure resistance ofthe refrigerating cycle is therefore optimized only when the channelcontrol valve 46 is open or closed, resulting in lower systemefficiency.

Yet another drawback is that the cooling system circuits can be switchedby opening and closing the channel control valve 46, but when a switchover is made from a circuit that passes through the first evaporator 44for the cooling of the refrigerator compartment to a circuit thatcreates a bypass through the second evaporator 45 for the cooling of thefreezer compartment, the refrigerant present in the first evaporator 44moves into the second evaporator 45, and if the arrangement is such thatthe first evaporator 44 is disposed below the second evaporator 45, orthe line-pass pattern of the first evaporator 44 has a structure inwhich a liquid trap is formed (for example, a structure whose passpattern is such that a plurality of rows or tube runs go from top tobottom and then back to the top), the refrigerant is propelled as aresult of vaporization and condensation rather than being propelleddirectly in the liquid state, so a comparatively long time elapses andthe machine oil tends to stay in the first evaporator, necessitating anincrease in the amount of sealed machine oil.

Another feature is that, for example, a top-freezer refrigerator isconfigured such that the first evaporator is disposed below the secondevaporator, but because the refrigerant and the machine oil present inthe first evaporator when the channel control valve is closed havedifficulty returning to the second evaporator in the top position andtend to stay in the first evaporator due to the effect of gravity, thesystem tends to operate with an insufficient amount of refrigerant ormachine oil following valve switching, creating drawbacks in terms ofcooling performance or compressor reliability.

A drawback, therefore, is that a gas deficit is created during theswitching of the channel control valve 46, or the refrigerant must besealed in a larger amount, leading to increased electric consumption andhigher costs.

Still another drawback is that the cooling system must be welded in alarger number of locations, and costs are increased as a result ofincreased labor requirements.

The present invention has been developed to overcome the above-describeddisadvantages.

It is accordingly an objective of the present invention to provide animproved refrigerator capable of properly regulating the temperaturewithin a low-temperature storage chamber independently of loadvariations and preventing a refrigerator compartment from reducing intemperature below a set value.

Another objective of the present invention is to provide a refrigeratorhaving an enhanced cooling performance.

Yet another objective of the present invention is to provide arefrigerator having optimally designed pressure reduction means and amore effective cooling system.

Still another objective of the present invention is to provide arefrigerator capable of reducing a gas deficit during the switching of achannel control valve and rendering the cooling system more effective.

A further objective of the present invention is to provide a low-costrefrigerator for which less labor is needed to assemble the coolingsystem.

DISCLOSURE OF THE INVENTION

In accomplishing the above and other objectives, a refrigeratoraccording to the present invention has a refrigerator compartment and afreezer compartment both defined therein, wherein the refrigeratorcompartment has a low-temperature storage chamber of a temperature lowerthan that of the refrigerator compartment. The refrigerator includes acompressor, a condenser, a first throttling device, a channel controlvalve, a refrigerator cooling unit, and a freezer cooling unit connectedin series to form a refrigerating cycle. The refrigerator cooling unitand the freezer cooling unit are accommodated in the refrigeratorcompartment and the freezer compartment, respectively. The refrigeratoralso includes a second throttling device connected in parallel with therefrigerator cooling unit, a first air fan for sending cold airheat-exchanged by the refrigerator cooling unit to the refrigeratorcompartment, a second air fan for sending cold air heat-exchanged by thefreezer cooling unit to the freezer compartment, a suction duct forintroducing air inside the refrigerator compartment to the refrigeratorcooling unit, a discharge duct for introducing air cooled by therefrigerator cooling unit into the refrigerator compartment and into thelow-temperature storage chamber, and an electrically-operated damperaccommodated in the discharge damper. When the electrically-operateddamper is open, an amount of air to be introduced into thelow-temperature storage chamber is greater than an amount of air to beintroduced into the refrigerator compartment, making it possible to coolthe low-temperature chamber more quickly than the refrigeratorcompartment and to appropriately regulate the temperature within thelow-temperature compartment independently of load variations.

The first air fan preferably has a varying capacity and can be operatedat one of a first speed and a second speed higher than the first speed.When the low-temperature storage chamber is cooled, the first air fan isoperated at the first speed to send a reduced amount of air to therefrigerator cooling unit. Accordingly, the temperature of airintroduced into the low-temperature storage chamber becomes low,enhancing the cooling efficiency for the low-temperature storagechamber.

The compressor may likewise have a varying capacity and can be operatedat one of a first speed and a second speed higher than the first speed.In this case, when the low-temperature storage chamber is cooled, thecompressor is operated at the second speed to lower the temperature ofevaporation in the refrigerator cooling unit, thereby lowering thetemperature of air heat-exchanged by the refrigerator cooling unit. As aresult, the temperature of air introduced into the low-temperaturestorage chamber becomes low, enhancing the cooling efficiency for thelow-temperature storage chamber.

The refrigerator preferably includes a timer, a first temperaturedetector for detecting the temperature within the refrigeratorcompartment, and a second temperature detector for detecting thetemperature within the low-temperature storage chamber.

By this construction, when the temperature detected by the firsttemperature detector is higher than a set temperature of therefrigerator compartment and when the temperature detected by the secondtemperature detector is higher than a set temperature of thelow-temperature storage chamber, operation of the first air fan isstarted, and the electrically-operated damper is opened after a lapse oftime recorded by the timer.

Upon cooling of the refrigerator compartment and after the temperatureof air heat-exchanged by the refrigerator cooling unit has been lowered,the cooling of the low-temperature storage chamber is started, making itpossible to narrow the width of temperature variations in thelow-temperature storage chamber.

Alternatively, when the temperature detected by the first temperaturedetector becomes lower than a set temperature of the refrigeratorcompartment and when the temperature detected by the second temperaturedetector becomes lower than a set temperature of the low-temperaturestorage chamber, the channel control valve is closed and operation ofthe first air fan is stopped after a lapse of time recorded by thetimer.

By this construction, After the channel control valve has been closed,the refrigerant present in the refrigerator cooling unit evaporatesimmediately, and cold air is uniformly drawn into the refrigeratorcompartment through discharge ports, thus preventing a lower portion ofthe refrigerator compartment from reducing in temperature below a settemperature.

The channel control valve may be opened simultaneously with a stop ofthe compressor, and the first air fan is operated for a predeterminedperiod of time. By so doing, even if the refrigerant flows into therefrigerator cooling unit, it evaporates immediately, and cold air isuniformly drawn into the refrigerator compartment through the dischargeports, thus preventing a lower portion of the refrigerator compartmentfrom reducing in temperature below a set temperature.

Alternatively, when the temperature detected by the first temperaturedetector is higher than a set temperature of the refrigeratorcompartment and when the temperature detected by the second temperaturedetector is higher than a set temperature of the low-temperature storagechamber, the channel control valve is opened and operation of the firstair fan is started after a lapse of predetermined time.

Because the cooling is started after the temperature of the refrigeratorcooling unit has been sufficiently lowered, the interior of thelow-temperature storage chamber is cooled with low-temperature cold airimmediately after the start of cooling of the low-temperature storagecompartment, enhancing the cooling efficiency for the low-temperaturestorage chamber.

Advantageously, the refrigerator includes a heater accommodated in thedischarge duct. The heater is supplied with electricity, when thetemperature detected by the first temperature detector becomes a settemperature of the refrigerator compartment before the temperaturedetected by the second temperature detector becomes a set temperature ofthe low-temperature storage chamber.

By this construction, even if the cooling load in the refrigeratorcompartment is low, for example, when the temperature of the open air islow, or even if the cooling load in the low-temperature storage chamberbecomes high when foods have been stored therein, only air in thedischarge duct is heated, avoiding a temperature drop below the settemperature in the refrigerator compartment, while cooling thelow-temperature storage chamber down to the set temperature.

A plurality of illumination lamps accommodated in the discharge duct maybe substituted for the heater, resulting in a reduction in themanufacturing cost.

In another form of the present invention, a refrigerator includes acompressor, a condenser, a first pressure reduction means, a channelcontrol valve, a first evaporator accommodated in the refrigeratorcompartment, and a second evaporator accommodated in the freezercompartment, all of which are connected in series to form arefrigerating cycle. The refrigerator also includes a bypass conduithaving a second pressure reduction means for connecting a flow-dividingportion positioned between the first pressure reduction means and thechannel control valve, and a flow-merging portion positioned between thefirst evaporator and the second evaporator, wherein a pressure reductionof the first pressure reduction means is greater than that of the secondpressure reduction means.

According to the above structure, the flow rate to the first evaporatordoes not change with the refrigerant state because it is possible toavoid situations in which the refrigerant is throttled for the secondtime in the comparatively narrow line after passing through the firstpressure reduction means when the channel control valve is open.

In addition, the resistance value of the second pressure reduction meansis set higher than the combined resistance value of the flow ratecontrol valve and the first evaporator (the resistance value of the flowrate control valve and the evaporator is commonly very low), so therefrigerant proceeds into the first evaporator with virtually noresistance.

Cooling performance can thus be enhanced without creating any shortagein terms of the cooling of the refrigerator compartment or the flow rateof the refrigerant entering the first evaporator for refrigerationcooling when such refrigeration cooling is required.

Also, the cooling performance is not reduced in any way because themanner in which the flow is divided does not change when the state ofthe refrigerant is changed by the heat effects demonstrated in thevicinity of the channel control valve.

Furthermore, the resistance value of the second pressure reduction meansshould be set above the very low combined resistance value of the flowrate control valve and the first evaporator to prevent the pressurereduction from varying widely due to the opening and closing of thechannel control valve. The reduced-pressure resistance of therefrigerating cycle can thus be optimized, and system efficiencyincreased.

Conveniently, heat is exchanged between a pipe connecting the secondevaporator and the compressor, and the first pressure reduction means,whereby the line connected to the compressor is heated to preventfrosting, to enhance the cooling effect of the refrigerating cycle, andto improve the cooling performance.

Again conveniently, heat is exchanged between the first pressurereduction means and a pipe connecting the first evaporator and thesecond evaporator, enhancing the cooling effect of the refrigeratingcycle and providing better cooling performance.

When the freezer compartment is positioned below the refrigeratorcompartment, it is preferred that the first evaporator be disposed abovethe second evaporator and have a pass pattern in which a plurality oftube runs are sequentially arranged in a single direction from top ofthe first evaporator downward, thereby preventing liquid traps fromforming. In this case, the refrigerant present in the first evaporatoris smoothly transported to the second evaporator by the pressuredifference and gravity when a switching is made by the opening orclosing of the channel control valve from a circuit that passes throughthe first evaporator for refrigerator cooling to a circuit that createsa bypass through the second evaporator for freezer cooling.

The efficiency of the cooling system can therefore be enhanced byavoiding a situation in which a significant gas deficit is produced inthe second evaporator during the switching of the channel control valveor the amount of sealed refrigerant must be increased.

Advantageously, the first evaporator is of a fin-coil-type one disposednear a cold air circulation means and has a plurality of tube runs, ofwhich neighboring tube runs are shifted from each other by apredetermined pitch to form a staggered layout, allowing the fin coil tooccupy a wider projected area in a cross section perpendicular to thedirection of air flow without forming liquid traps in the firstevaporator. In addition, the heat-transfer coefficient can be increasedby the enhanced turbulence around the tube runs, and the efficiency ofthe cooling system can be increased.

Again advantageously, the flow-dividing portion, the second pressurereduction means, and the flow-merging portion are disposed in therefrigerator compartment, whereby the number of welded connections inthe freezer compartment is minimized (reduced to two) by employing asimple structure in which the second evaporator is merely connected withthe inlet and outlet lines.

Work is thus facilitated in the comparatively inaccessible secondevaporator below the first evaporator.

In addition, the first evaporator, channel control valve, secondpressure reduction means, flow-dividing portion, and flow-mergingportion can be integrated into a single unit, allowing thissub-assembled unit to be incorporated into the system itself merely byperforming welding at two locations. It is also possible to cut down onlabor and to improve welding reliability.

In yet another form of the present invention, a refrigerator has arefrigerator compartment, a freezer compartment, and a machine chamberall defined therein, wherein the refrigerator compartment is formedabove the freezer compartment, and the machine chamber is formed at alower portion of the freezer compartment. The refrigerator includes afirst cold air circulation means and a first evaporator both located ona surface deep inside the refrigerator compartment, and a second coldair circulation means and a second evaporator both located on a surfacedeep inside the freezer compartment, with the second evaporator disposedbelow the first evaporator.

With this arrangement, the refrigerant or machine oil inside the firstevaporator gradually returns to the second evaporator in the directionof gravity when the supply of refrigerant to the first evaporator isstopped by the switching of the channel control valve. A smooth returnof the refrigerant is thus facilitated, and it is unlikely that therefrigerant stays in the first evaporator, preventing the coolingperformance or reliability from being adversely affected while avoidingsituations in which the system operates with a shortage of therefrigerant or machine oil.

Alternatively, the machine chamber is formed at a lower portion of thefreezer compartment, while the second cold air circulation means and thesecond evaporator are located at another lower portion of the freezercompartment in front of the machine chamber, whereby the interior of thefreezer compartment can be used freely as a storage space, and thedifficult-to-use portion of the bottom of the refrigerator body can beused as a space for accommodating the machine chamber and the secondevaporator, making it possible to configure the inactive capacity in amore efficient manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objectives and features of the present inventionwill become more apparent from the following description of preferredembodiments thereof with reference to the accompanying drawings,throughout which like parts are designated by like reference numerals,and wherein:

FIG. 1 is a vertical sectional view of a conventional refrigerator;

FIG. 2 is a block diagram of a refrigerating cycle employed in anotherconventional refrigerator;

FIG. 3 is a vertical sectional view of a first embodiment of arefrigerator according to the present invention;

FIG. 4 is a block diagram of a refrigerating cycle employed in therefrigerator of FIG. 3;

FIG. 5 is a schematic front view of a discharge duct mounted in therefrigerator of FIG. 3;

FIG. 6 is a timing chart used to control the refrigerator of FIG. 3;

FIG. 7 is a chart similar to FIG. 6, but depicting a modificationthereof;

FIG. 8 is a chart similar to FIG. 6, but depicting another modificationthereof;

FIG. 9 is a chart similar to FIG. 6, but depicting a furthermodification thereof;

FIG. 10 is a chart similar to FIG. 6, but depicting a still furthermodification thereof;

FIG. 11 is a chart similar to FIG. 6, but depicting another modificationthereof;

FIG. 12 is a chart similar to FIG. 6, but depicting still anothermodification thereof;

FIG. 13A is a view similar to FIG. 5, but particularly depicting adischarge duct having a heater mounted therein;

FIG. 13B is a vertical sectional view of the discharge duct of FIG. 13A;

FIG. 14A is a view similar to FIG. 5, but particularly depicting anotherdischarge duct having a plurality of illumination lamps mounted therein;

FIG. 14B is a vertical sectional view of the discharge duct of FIG. 14A;

FIG. 15 is a vertical sectional view of a second embodiment of therefrigerator according to the present invention;

FIG. 16 is a block diagram of a refrigerating cycle employed in therefrigerator of FIG. 15;

FIG. 17 is a view similar to FIG. 15, but depicting a third embodimentof the refrigerator according to the present invention;

FIG. 18 is a view similar to FIG. 15, but depicting a fourth embodimentof the refrigerator according to the present invention;

FIG. 19 is a schematic perspective view of a first evaporator and otherelements in the vicinity thereof, which are mounted in the refrigeratorof FIGS. 15, 17 or 18;

FIG. 20 is a view similar to FIG. 19, but depicting a modificationthereof;

FIG. 21 is a view similar to FIG. 19, but depicting another modificationthereof;

FIG. 22 is a vertical sectional view of a fifth embodiment of therefrigerator according to the present invention; and

FIG. 23 is a vertical sectional view of a sixth embodiment of therefrigerator according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This application is based on application Nos. 10-38405 and 10-39949filed in Japan on Feb. 20 and 23, 1998, respectively, the content ofwhich is incorporated hereinto by reference.

Referring now to the drawings, there is shown in FIG. 3 a bottom-freezerrefrigerator embodying the present invention, which includes arefrigerator body 101 having a cold storage or refrigerator compartment102 and a freezer compartment 103 both defined therein at upper andlower portions thereof, respectively. The refrigerator compartment 102and the freezer compartment 103 are opened and closed by doors 104 and105, respectively, hingedly mounted on a front surface of therefrigerator body 101.

A cooler chamber 121 is formed at a rear portion of the freezercompartment 103 and accommodates a freezer cooling unit 108 forproducing cold air and an air fan 107 for sending the cold air.

The refrigerator compartment 102 is partitioned by partition plates intoa plurality of small compartments, in which foods are stored. Avegetable storage chamber or crisper 106, in which vegetables are mainlystored, is formed at a lower portion of the refrigerator compartment102, while a low-temperature storage chamber 133 is formed above thevegetable storage chamber 106. The temperature within thelow-temperature storage chamber 133 is generally set to a value lowerthan the temperature within the refrigerator compartment 102 and thatwithin the vegetable storage chamber 106. By way of example, thetemperature within the refrigerator compartment 102 is set in the rangeof 2° C. to 4° C., while that within the low-temperature storage chamber133 is set in the range of −4° C. to −2° C. The temperature within thefreezer compartment 103 is set in the range of −21° C. to −17° C.

A temperature sensor S1 for detecting the temperature within therefrigerator compartment 102 is provided at a rear portion of therefrigerator compartment 102, while a temperature sensor S2 fordetecting the temperature within the low-temperature storage chamber 133is provided at a rear portion of the low-temperature storage chamber133. A temperature sensor S3 for detecting the temperature within thefreezer compartment 103 is provided at a rear portion of the freezercompartment 103.

A cooler chamber 120 is formed at a rear portion of the refrigeratorcompartment 102 and accommodates a refrigerator cooling unit 110 forproducing cold air, an air fan 109 for sending the cold air, a suctionduct 115 for introducing the air inside the refrigerator compartment 102to the refrigerator cooling unit 110, and a discharge duct 116 forintroducing the air heat-exchanged and cooled by the refrigeratorcooling unit 110 into the refrigerator compartment 102.

FIG. 4 depicts a refrigerating cycle employed in the refrigerator ofFIG. 3. As shown therein, the refrigerating cycle is formed byconnecting a compressor 111, a condenser 112, a first throttling device113, a channel switching or channel control valve 122, the refrigeratorcooling unit 110, and the freezer cooling unit 108 in series in thisorder and by connecting a second throttling device 124 in parallel withthe refrigerator cooling unit 110. The channel control valve 122controls a flow of refrigerant into the refrigerator cooling unit 110.

As shown in FIG. 5, the discharge duct 116 accommodates the air fan 109and an electrically-operated damper 140. The temperature within thelow-temperature storage chamber 133 is controlled by the operation ofthe electrically-operated damper 140. The discharge duct 116 has coldair outlets 138 defined therein at upper portions thereof, through whichcold air is discharged into the refrigerator compartment 102. Thedischarge duct 116 also has cold air outlets 135 defined therein belowthe electrically-operated damper 140 so that cold air is discharged intothe low-temperature storage chamber 133 through the cold air outlets135.

In the above-described construction, when the refrigerator compartment102 and the low-temperature storage chamber 133 are cooled, theoperation of the compressor 111 and that of the air fan 109 are started,and the channel control valve 122 is opened to introduce the refrigerantinto the refrigerator cooling unit 110. The air inside the refrigeratorcompartment 102 is drawn into the refrigerator cooling unit 110 throughthe suction duct 115 and is cooled by the latent heat of evaporation ofthe refrigerant inside the refrigerator cooling unit 110. When theelectrically-operated damper 140 is opened, the air cooled by therefrigerator cooling unit 110 is divided into two at an upper portion ofthe air fan 109. A portion of the air is introduced into therefrigerator compartment 102 through the cold air outlets 138, while theother portion of the air passes through the electrically-operated damper140 and is introduced into the low-temperature storage chamber 133through the cold air outlets 135.

At this moment, because air flowing through the upper portion of the airfan 109 receives dynamic pressures in a direction of rotation of the airfan 109, a large amount of air is directed towards theelectrically-operated damper 140 and is then introduced into thelow-temperature storage chamber 133. Accordingly, the low-temperaturestorage chamber 133 is cooled down to a set temperature more quicklythan the refrigerator compartment 102. When the low-temperature storagechamber 133 has been cooled down to the set temperature, theelectrically-operated damper 140 is closed and, hence, all the air sentby the air fan 109 is introduced into the refrigerator compartment 102through the cold air outlets 138 to cool it down to a set temperature.

As discussed hereinabove, because the low-temperature storage chamber133 is cooled more quickly than the refrigerator compartment 102 byvirtue of a high distribution ratio of air, the temperature within thelow-temperature storage chamber 133 can be controlled independently ofload variations.

FIG. 6 depicts a timing chart, based on which the refrigerator accordingto the present invention is controlled. The air fan 109, controlledaccording to the timing chart of FIG. 6, has a varying capacity.

At the outset, the compressor 111 and the air fans 107, 109 are all at astandstill, while the channel control valve 122 and theelectrically-operated damper 140 are both closed. The temperature withinthe refrigerator compartment 102, that within the low-temperaturestorage chamber 133, and that within the freezer compartment 103 aredetected by the temperature sensors S1, S2, and S3, respectively.

When the temperature within the freezer compartment 103 detected by thetemperature sensor S3 exceeds an upper limit of its predeterminedtemperature range, the operation of the compressor 111 and that of theair fan 107 are started. At this moment, if the temperature within therefrigerator compartment 102 detected by the temperature sensor S1exceeds an upper limit of its predetermined temperature range, thechannel control valve 122 is opened, and the operation of the air fan109 is started at a high speed. In addition, if the temperature withinthe low-temperature storage chamber 133 detected by the temperaturesensor S2 exceeds an upper limit of its predetermined temperature range,the electrically-operated damper 140 is opened, and the air fan 109 isoperated at a low speed. By so doing, the refrigerant is introduced intothe refrigerator cooling unit 110 and then into the freezer cooling unit108 to cool the freezer compartment 103, the refrigerator compartment102, and the low-temperature storage chamber 133.

When the detected temperature within the low-temperature storage chamber133 becomes lower than a lower limit of its predetermined temperaturerange, the electrically-operated damper 140 is closed, and the air fan109 is operated at the high speed. Since then, the low-temperaturestorage chamber 133 is no longer cooled. If the detected temperaturewithin the freezer compartment 103 and that within the refrigeratorcompartment 102 become lower than respective lower limits of thepredetermined temperature ranges, the air fan 107 and the air fan 109are stopped, respectively. The compressor 111 is stopped simultaneouslywith the air fan 107.

As described above, when the low-temperature storage chamber 133 iscooled, the air fan 109 is operated at a low speed. As a result, theamount of air flowing through the refrigerator cooling unit 110 isreduced and, hence, the temperature of air introduced into thelow-temperature storage chamber 133 becomes low, thus reducing thecooling time of the low-temperature storage chamber 133. Accordingly,even when the cooling load in the refrigerator compartment 102 is low,for example, when the temperature of the open air is low, thelow-temperature storage chamber 133 can be cooled down to the settemperature within a reduced period of time of operation of the air fan109.

The refrigerator according to the present invention may be controlledbased on another timing chart as shown in FIG. 7. The compressor 111,controlled according to the timing chart of FIG. 7, has a varyingcapacity.

When the detected temperature within the freezer compartment 103 exceedsan upper limit of its predetermined temperature range, the operation ofthe compressor 111 and that of the air fan 107 are started. At thismoment, if the detected temperature within the refrigerator compartment102 exceeds an upper limit of its predetermined temperature range, thechannel control valve 122 is opened, and the operation of the air fan109 is started. In addition, if the detected temperature within thelow-temperature storage chamber 133 exceeds an upper limit of itspredetermined temperature range, the electrically-operated damper 140 isopened, and the compressor 111 is operated at a high speed. By so doing,the refrigerant is introduced into the refrigerator cooling unit 110 andthen into the freezer cooling unit 108 to cool the freezer compartment103, the refrigerator compartment 102, and the low-temperature storagechamber 133.

When the detected temperature within the low-temperature storage chamber133 becomes lower than a lower limit of its predetermined temperaturerange, the electrically-operated damper 140 is closed, and thecompressor 111 is operated at a low speed. If the detected temperaturewithin the freezer compartment 103 and that within the refrigeratorcompartment 102 become lower than respective lower limits of thepredetermined temperature ranges, the air fan 107 and the air fan 109are stopped, respectively. The compressor 111 is stopped simultaneouslywith the air fan 107.

As described above, when the low-temperature storage chamber 133 iscooled, the compressor 111 is operated at a high speed. As a result, thetemperature of evaporation in the refrigerator cooling unit 110 becomeslow and, hence, both the temperature of air passing through therefrigerator cooling unit 110 and that of air introduced into thelow-temperature storage chamber 133 drop, thus reducing the cooling timeof the low-temperature storage chamber 133. Accordingly, even when thecooling load in the refrigerator compartment 102 is low, for example,when the temperature of the open air is low, the low-temperature storagechamber 133 can be cooled down to the set temperature within a reducedperiod of time of operation of the air fan 109.

FIG. 8 depicts a further timing chart, based on which the refrigeratoraccording to the present invention is controlled.

When the detected temperature within the freezer compartment 103 exceedsan upper limit of its predetermined temperature range, the operation ofthe compressor 111 and that of the air fan 107 are started. At thismoment, if the detected temperature within the refrigerator compartment102 exceeds an upper limit of its predetermined temperature range, thechannel control valve 122 is opened, and the operation of the air fan109 is started. In addition, if the detected temperature within thelow-temperature storage chamber 133 exceeds an upper limit of itspredetermined temperature range, a timer is activated. By so doing, therefrigerant is introduced into the refrigerator cooling unit 110 andthen into the freezer cooling unit 108 to start cooling the freezercompartment 103 and the refrigerator compartment 102. When the timertimes out or records a predetermined period of time, theelectrically-operated damper 140 is opened, and the cooling of thelow-temperature storage chamber 133 is started.

When the detected temperature within the low-temperature storage chamber133 becomes lower than a lower limit of its predetermined temperaturerange, the electrically-operated damper 140 is closed. If the detectedtemperature within the freezer compartment 103 and that within therefrigerator compartment 102 become lower than respective lower limitsof the predetermined temperature ranges, the air fan 107 and the air fan109 are stopped, respectively. The compressor 111 is stoppedsimultaneously with the air fan 107.

As described above, when the cooling of the low-temperature storagechamber 133 is desired, the opening of the electrically-operated damper140 is delayed by a predetermined period of time, thereby cooling therefrigerator compartment 102 prior to the cooling of the low-temperaturestorage chamber 133. When the electrically-operated damper 140 isopened, the temperature within the refrigerator cooling unit 110 dropssufficiently. At this moment, the temperature of air having passed therefrigerator cooling unit 110 is lower than that within thelow-temperature storage chamber 133 and, hence, the low-temperaturestorage chamber 133 is cooled by low-temperature air from the start ofthe cooling, making it possible to reduce the cooling time of thelow-temperature storage chamber 133 and reduce the width of temperaturevariations in the low-temperature storage chamber 133.

It is to be noted here that the electrically-operated damper 140 can besimilarly controlled using the detected temperature of the refrigeratorcooling unit 110, that of air discharged into the refrigeratorcompartment 102 or the like.

FIG. 9 depicts a still further timing chart, based on which therefrigerator according to the present invention is controlled.

When the detected temperature within the freezer compartment 103 exceedsan upper limit of its predetermined temperature range, the operation ofthe compressor 111 and that of the air fan 107 are started. At thismoment, if the detected temperature within the refrigerator compartment102 exceeds an upper limit of its predetermined temperature range, thechannel control valve 122 is opened, and the operation of the air fan109 is started. In addition, if the detected temperature within thelow-temperature storage chamber 133 exceeds an upper limit of itspredetermined temperature range, the electrically-operated damper 140 isopened. By so doing, the refrigerant is introduced into the refrigeratorcooling unit 110 and then into the freezer cooling unit 108 to cool thefreezer compartment 103, the refrigerator compartment 102, and thelow-temperature storage chamber 133.

When the detected temperature within the low-temperature storage chamber133 becomes lower than a lower limit of its predetermined temperaturerange, the electrically-operated damper 140 is closed, thereby coolingonly the refrigerator compartment 102. If the detected temperaturewithin the refrigerator compartment 102 becomes lower than a lower limitof the predetermined temperature range, the channel control valve 122 isclosed and a timer is activated. When the timer times out or records apredetermined period of time, the operation of the air fan 109 isstopped. If the detected temperature within the freezer compartment 103becomes lower than a lower limit of the predetermined temperature range,the operation of the air fan 107 and that of the compressor 111 aresimultaneously stopped.

As described above, because the operation of the air fan 109 continueseven after the channel control valve 122 has been closed, therefrigerant remaining in the refrigerator cooling unit 110 evaporatesimmediately, and the cold air flows uniformly into the refrigeratorcompartment 102 through the cold air outlets 138, thus eliminating aproblem of lowering the temperature of a lower portion of therefrigerator compartment 102 below a set temperature. This problem hasbeen hitherto caused by the refrigerant remaining in the refrigeratorcooling unit 110 after the channel control valve 122 has been closed.Such refrigerant acts to cool the air around the refrigerator coolingunit 110, which air in turn flows downwardly to the lower portion of therefrigerator compartment 102 through the suction duct 115 by convectionand lowers the temperature thereof.

Furthermore, the latent heat of sublimation or fusion of dewdropsadhering to the refrigerator cooling unit 110 can be utilized for thecooling of the refrigerator compartment 102, making it possible toreduce the power consumption.

Also, because the quantity of dewdrops adhering to the refrigeratorcooling unit 110 per unit cooling time of the refrigerator cooling unit110 is reduced, the period of time required to defrost the refrigeratorcooling unit 110 can be prolonged, resulting in a reduction in powerconsumption.

FIG. 10 depicts another timing chart that is used to control therefrigerator according to the present invention.

When the detected temperature within the freezer compartment 103 exceedsan upper limit of its predetermined temperature range, the operation ofthe compressor 111 and that of the air fan 107 are started. At thismoment, if the detected temperature within the refrigerator compartment102 exceeds an upper limit of its predetermined temperature range, thechannel control valve 122 is opened, and the operation of the air fan109 is started. In addition, if the detected temperature within thelow-temperature storage chamber 133 exceeds an upper limit of itspredetermined temperature range, the electrically-operated damper 140 isopened. By so doing, the refrigerant is introduced into the refrigeratorcooling unit 110 and then into the freezer cooling unit 108 to cool thefreezer compartment 103, the refrigerator compartment 102, and thelow-temperature storage chamber 133.

When the detected temperature within the low-temperature storage chamber133 becomes lower than a lower limit of its predetermined temperaturerange, the electrically-operated damper 140 is closed, thereby coolingonly the refrigerator compartment 102. If the detected temperaturewithin the refrigerator compartment 102 becomes lower than a lower limitof the predetermined temperature range, the channel control valve 122 isclosed and the operation of the air fan 109 is stopped. If the detectedtemperature within the freezer compartment 103 becomes lower than alower limit of the predetermined temperature range, the operation of theair fan 107 is stopped. The compressor 111 is stopped simultaneouslywith the air fan 107.

When the compressor 111 is stopped, a timer is activated. At thismoment, the channel control valve 122 is opened, while the operation ofthe air fan 109 is started. When the timer records a predeterminedperiod of time, the air fan 109 is stopped.

As described above, because the channel control valve 122 is openedsimultaneously with a stop of the compressor 111, even if therefrigerant flows into the refrigerator cooling unit 110, therefrigerant evaporates immediately, and cold air flows uniformly intothe refrigerator compartment 102 through the cold air outlets 138, thuspreventing the temperature of the lower portion of the refrigeratorcompartment 102 from dropping below the set temperature.

FIG. 11 depicts still another timing chart that is used to control therefrigerator according to the present invention.

When the detected temperature within the freezer compartment 103 exceedsan upper limit of its predetermined temperature range, the operation ofthe compressor 111 and that of the air fan 107 are started. At thismoment, if the detected temperature within the refrigerator compartment102 exceeds an upper limit of its predetermined temperature range, thechannel control valve 122 is opened to allow the refrigerant to flowinto the refrigerator cooling unit 110. In addition, if the detectedtemperature within the low-temperature storage chamber 133 exceeds anupper limit of its predetermined temperature range, a timer isactivated. When the timer records a predetermined period of time, theoperation of the air fan 109 is started, and the electrically-operateddamper 140 is opened, thereby cooling the refrigerator compartment 102and the low-temperature storage chamber 133.

When the detected temperature within the low-temperature storage chamber133 becomes lower than a lower limit of its predetermined temperaturerange, the electrically-operated damper 140 is closed. If the detectedtemperature within the freezer compartment 103 and that within therefrigerator compartment 102 become lower than respective lower limitsof the predetermined temperature ranges, the air fans 107 and 109 arestopped, respectively. The compressor 111 is stopped simultaneously withthe air fan 107.

As described above, when the cooling of the low-temperature storagechamber 133 is started simultaneously with the cooling of therefrigerator compartment 102, the operation of the air fan 109 isdelayed by the predetermined period of time, and after the temperaturewithin the refrigerator cooling unit 110 has dropped sufficiently, boththe refrigerator compartment 102 and the low-temperature storage chamber133 are cooled by operating the air fan 109. Accordingly, thetemperature of air having passed the refrigerator cooling unit 110 islower than the temperature within the low-temperature storage chamber133. By so doing, the low-temperature storage chamber 133 is cooled withthe low-temperature air from the start of the cooling, making itpossible to reduce the cooling time of the low-temperature storagechamber 133 and reduce the width of temperature variations in thelow-temperature storage chamber 133.

FIG. 12 depicts another timing chart that is used to control therefrigerator according to the present invention.

When the detected temperature within the freezer compartment 103 exceedsan upper limit of its predetermined temperature range, the operation ofthe compressor 111 and that of the air fan 107 are started. At thismoment, if the detected temperature within the refrigerator compartment102 exceeds an upper limit of its predetermined temperature range, thechannel control valve 122 is opened, and the operation of the air fan109 is started. In addition, if the detected temperature within thelow-temperature storage chamber 133 exceeds an upper limit of itspredetermined temperature range, the electrically-operated damper 140 isopened. By so doing, the refrigerant is introduced into the refrigeratorcooling unit 110 and then into the freezer cooling unit 108 to cool thefreezer compartment 103, the refrigerator compartment 102, and thelow-temperature storage chamber 133.

If the detected temperature within the refrigerator compartment 102becomes lower than a lower limit of the predetermined temperature rangebefore the detected temperature within the low-temperature storagechamber 133 becomes lower than a lower limit of the predeterminedtemperature range, a heater 142 accommodated in the discharge duct 116is supplied with electricity.

As shown in FIG. 13, the heater 142 is mounted on the inner surface ofthe discharge duct 116 above the air fan 109. If the detectedtemperature within the low-temperature storage chamber 133 becomes lowerthan a lower limit of the predetermined temperature range, theelectrically-operated damper 140 and the channel control valve 122 areboth closed, and the operation of the air fan 109 is stopped. At thismoment, electric supply to the heater 142 is also stopped. If thedetected temperature within the freezer compartment 103 becomes lowerthan a lower limit of the predetermined temperature range, the air fan107 is stopped. The compressor 111 is stopped simultaneously with theair fan 107.

As described above, when the refrigerator compartment 102 has beencooled more quickly than the low-temperature storage chamber 133, onlyair discharged into the refrigerator compartment 102 through the coldair outlets 138 is heated by the heater 142. Accordingly, even if thecooling load in the refrigerator compartment 102 is low, for example,when the temperature of the open air is low, or even if the cooling loadin the low-temperature storage chamber 133 becomes high when foods havebeen stored therein, a temperature drop below the set temperature in therefrigerator compartment 102 is prevented, while the low-temperaturestorage chamber 133 is cooled down to the set temperature.

The heater 142 shown in FIG. 13 may be replaced with a plurality ofillumination lamps 141, as shown in FIGS. 14A and 15B. The plurality ofillumination lamps 141 are accommodated in the discharge duct 116 atpositions upstream of the cold air outlets 138 with respect to thedirection of flow of the air.

The illumination lamps 141 are turned on, when the door 104 is opened,to illuminate foods stored in the refrigerator compartment 102. Theselamps 141 are also turned on, when the refrigerator compartment 102 iscooled more quickly than the low-temperature storage chamber 133, toheat the air discharged into the refrigerator compartment 102 throughthe cold air outlets 138. The illumination lamps 141 are turned offsimultaneously when the cooling of the low-temperature storage chamber133 has been terminated.

The use of the illumination lamps 141 in place of the heater 142 forcontrolling the temperature within the refrigerator compartment 102contributes to a reduction in the manufacturing cost of therefrigerator.

It is, however, to be noted that the illumination lamps 141 can be usedtogether with the heater 142.

FIG. 15 depicts a second embodiment of a bottom-freezer refrigeratoraccording to the present invention.

As shown in FIG. 15, the refrigerator includes a refrigerator body 150having a refrigerator compartment 163 and a freezer compartment 162 bothdefined therein at upper and lower portions thereof, respectively. Therefrigerator compartment 163 and the freezer compartment 162 are openedand closed by respective doors (not shown) hingedly mounted on a frontsurface of the refrigerator body 150.

As shown in FIG. 16, a compressor 151, a condenser 152, a firstcapillary 153 (first pressure reduction means), a self-holdingmotor-operated valve 156 (channel control valve), a first evaporator154, and a second evaporator 155 are sequentially connected into arefrigerating cycle 164. The refrigerating cycle 164 is also composed ofa bypass conduit having a second pressure reduction means 157 forconnecting a flow-dividing portion 158 positioned between the firstpressure reduction means 153 and the motor-operated valve 156, and aflow-merging portion 159 positioned between the first evaporator 154 andthe second evaporator 155.

The line connecting the motor-operated valve 156, first evaporator 154,and second evaporator 155 has a radius that offers a relatively smallresistance to the passage of the refrigerant; for example, a line havingroughly the same diameter as lines in the evaporators.

In addition, the first evaporator 154 is located in the refrigeratorcompartment 163 (for example, on the surface deep inside therefrigerator compartment), and a refrigerator duct 166 and a firstmotor-operated fan 165 for circulating the internal air of therefrigerator compartment 163 by passing the air through the firstevaporator 154 are disposed in the vicinity.

Furthermore, the second evaporator 155 is located in the freezercompartment 162 (for example, on the surface deep inside the freezercompartment), and a freezer duct 168 and a second motor-operated fan 167for circulating the internal air of the freezer compartment 162 bypassing the air through the second evaporator 155 are disposed in thevicinity.

In addition, the motor-operated valve 156 is disposed inside therefrigerator compartment 163, and the flow-dividing portion 158 is alsopositioned inside the refrigerator compartment 163 (for example, in thevicinity of the motor-operated valve 156). The flow-merging portion 159is located inside the freezer compartment 162 (for example, in thevicinity of the second evaporator 155).

Although the second capillary 157 and the line connecting the secondcapillary 157, the first evaporator 154, and the second evaporator 155may be disposed inside or outside the apparatus, it is best to embedthese in the heat-insulated walls to reduce the loss of therefrigerating effect.

In addition, the resistance value of the first capillary 153 is suchthat there is no constriction between the motor-operated valve 156 andthe first evaporator 154, making it possible to select a capillarysuited to the refrigerating cycle when the motor-operated valve 156 isopen. For the second capillary 157, the setting is also higher than thetotal resistance value (pressure loss) of the motor-operated valve 156and the first evaporator 154.

The condenser 152 is located at least partially in a machine chamber169, and is configured for cooling with a third motor-operated fan 170provided in the vicinity.

The freezer compartment 162 and the refrigerator compartment 163 arealso provided with temperature sensing means (not shown) for sensing thetemperature in respective compartments, and with control means (notshown) for controlling the compressor 151, motor-operated valve 156,first motor-operated fan 165, second motor-operated fan 167, and thirdmotor-operated fan 170.

The operation of the refrigerating apparatus thus configured will now bedescribed.

When the temperature inside the freezer compartment 162 rises, thetemperature sensing means detects that a predetermined temperaturepresetting has been exceeded. The control means receives this signal andactuates the compressor 151, second motor-operated fan 167, thirdmotor-operated fan 170, and motor-operated valve 156.

The high-temperature, high-pressure refrigerant discharged by theoperation of the compressor 151 is condensed and liquefied by thecondenser 152 (which is cooled by the motor-operated fan 170), reducedin pressure by the first capillary 153, and delivered to theflow-dividing portion 158.

The motor-operated valve 156 opens when the temperature sensing means ofthe refrigerator compartment 163 detects that a predeterminedtemperature has been exceeded, and closes when the temperature is belowthe predetermined level. Similarly, the first motor-operated fan 165 isstarted when the temperature sensing means of the refrigeratorcompartment 163 detects that a predetermined temperature has beenexceeded, and is stopped when the temperature decreases below thepredetermined level.

When the motor-operated valve 156 is closed, the refrigerant is admittedthrough the flow-dividing portion 158 into the second capillary 157,reduced in pressure, and delivered to the second evaporator 155. The airinside the freezer compartment 162 is drawn in through the freezer duct168 by the operation of the second motor-operated fan 167, heat isexchanged thoroughly, and the refrigerant is vaporized and gasifiedinside the second evaporator 155. The gasified refrigerant is againdrawn into the compressor 151. The heat-exchanged air, which by now hasa lower temperature, is discharged.

When the temperature of air inside the freezer compartment 162 is thuslowered and the temperature sensing means detects that the temperaturedecreased below a predetermined level, the compressor 151, secondmotor-operated fan 167, and third motor-operated fan 170 are stopped bythe control means, and the motor-operated valve 156 is actuated andclosed.

In addition, when the temperature sensing means of the refrigeratorcompartment 163 detects that the predetermined temperature has beenexceeded, and the motor-operated valve 156 is opened, the refrigerantflows from the flow-dividing portion 158 through the motor-operatedvalve 156, reaches the first evaporator 154, and then enters the secondevaporator 155. Furthermore, part of the refrigerant in theflow-dividing portion 158 enters the second capillary 157, unites withthe aforementioned refrigerant stream in the flow-merging portion 159,and flows into the second evaporator 155. The refrigerant vaporized andgasified by the first evaporator 154 and second evaporator 155 isreadmitted into the compressor 151.

Th air inside the refrigerator compartment 163 is drawn in through therefrigerator duct 166 by the operation of the first motor-operated fan165, heat is exchanged thoroughly, and the refrigerant is partiallyvaporized and gasified inside the first evaporator 154. Theheat-exchanged air, which by now has a comparatively low temperature, isdischarged, and the temperature inside the refrigerator compartment 163is allowed to decrease. When the temperature sensing means detects thatthis temperature has decreased below the predetermined temperature, thefirst motor-operated fan 165 is stopped, and the motor-operated valve156 is actuated and closed.

Similarly, the freezer compartment 162 is cooled by the operation of thesecond motor-operated fan 167, and when the temperature sensing meansdetects that the temperature has dropped below the predetermined level,the compressor 151, second motor-operated fan 167, and thirdmotor-operated fan 170 are stopped by the control means, and themotor-operated valve 156 is actuated and closed.

In addition, using a self-holding motor-operated valve (channel controlvalve) and consuming power solely for actuation during opening orclosing are particularly effective from the standpoint of energyconservation. Furthermore, the noise is kept low because the drive meanscan, for example, be based on a pulse motor or other type of motor.

Cooling and temperature adjustment are accomplished by repeating suchprocedures. When the motor-operated valve 156 is open, the refrigerantpassing through the first capillary 153 flows through the flow-dividingportion 158 and the motor-operated valve 156 without being againrestricted by capillaries (comparatively narrow lines) before reachingthe first evaporator 154, and a connection is formed using a line whosediameter is roughly the same as that of the evaporators, avoidingsituations in which the flow rate into the first evaporator 154 isreduced by the entrainment of a gas-phase refrigerant when therefrigerant flows as a two-phase mixture and the void ratio varies as aresult of occasional load changes caused by the ambient temperatureconditions of the refrigerating apparatus, replacement of food, openingand closing of the door, and the like.

In addition, the resistance value of the second pressure reduction meansis set higher than the combined resistance value of the channel controlvalve and the first evaporator (the resistance value of the channelcontrol valve and the evaporator is commonly very low), so therefrigerant proceeds into the first evaporator with virtually noresistance. Cooling performance can thus be enhanced without creatingany shortage in terms of the cooling of the refrigerator compartment orthe flow rate of the refrigerant entering the aforementioned firstevaporator for refrigeration cooling when such refrigeration cooling isrequired.

In addition, the cooling performance is not reduced in any way becausethe manner in which the flow is divided does not change when the stateof the refrigerant is changed by the heat effects demonstrated in thevicinity of the channel control valve.

Furthermore, the resistance value of the second pressure reduction meansshould be set above the very low combined resistance value of thechannel control valve and the first evaporator to prevent the pressurereduction from varying widely due to the opening and closing of thechannel control valve. The reduced-pressure resistance of therefrigerating cycle can thus be optimized, and system efficiencyincreased.

A self-holding motor-operated valve was described as the channel controlvalve, but a low-cost solenoid valve, which has a simple structure andis easy to control, may also be used.

Embedding the motor-operated valve 156, the flow-dividing portion 158,and the flow-merging portion 159 in a heat-insulated wall is effectivefor preventing frost from forming on the motor-driven valve or the like.

The condenser may also be disposed outside the back surface of therefrigerator and cooled by natural convection. The same effect can beobtained with a so-called inner condenser, in which lines are placedbetween the back surface and the heat-insulated wall.

FIG. 17 depicts a third embodiment of a bottom-freezer refrigeratoraccording to the present invention. For structures that are the same asin the second embodiment, no detailed description will be given, andidentical symbols are used.

A heat exchanger 172 is provided for exchanging heat between the firstcapillary 153 and a suction pipe 171 connecting the second evaporator155 and the compressor 151. This heat exchanger 172 is embedded in aheat-insulated section on the back surface of the refrigerator body 150.In addition, the second capillary 157 is embedded in a heat-insulatedmaterial without any heat exchange.

The heat exchanger 172 may be bundled close together with the aid of atape or the like to prevent penetration of the heat-insulated material.Improvement of heat transfer by soldering is desired.

In addition, increasing the heat-exchange distance is beneficial forachieving adequate heat exchange, but the pressure loss in the suctionpipe 171 is increased and efficiency lowered when the distance is toolarge, so the distance is set between 1000 and 2000 mm.

Heat exchange is thus performed with the first capillary 153 before therefrigerant leaving the second evaporator 155 returns to the compressor151, and a higher temperature is established in the line leading to thecompressor 151 and being in contact with air in the vicinity thereof,making it possible to prevent condensation and arresting the formationof water drops.

In addition, cooling the refrigerant in the first capillary 153 enhancesthe cooling effect of the refrigerating cycle 164 and provides bettercooling performance.

Another feature is that the second capillary 157 is not subjected toheat exchange because when such heat exchange is performed, variationsin the amount of heat exchanged during the opening of the motor-operatedvalve 156 induce changes in the flow rate of the capillary and causemore refrigerant than necessary to be fed to the second evaporator 155,with the result that the amount in which the refrigerant is fed to thefirst evaporator 154 is reduced, and the first evaporator 154 deliversan inferior cooling performance.

FIG. 18 depicts a fourth embodiment of a bottom-freezer refrigeratoraccording to the present invention. For structures that are the same asin the second and third embodiments, no detailed description will begiven, and identical symbols will be used.

A heat exchanger 174 is provided for exchanging heat between the firstcapillary 153 and a connection pipe 173 connecting the first evaporator154 and the second evaporator 155. This heat exchanger 174 is embeddedin a heat-insulated section on the back surface of the refrigerator body150.

If the line length of the connection pipe 173 is increased, thearrangement of the line is complicated and liquid traps form or thepressure loss increases, making it desirable that the evaporators beconnected over the shortest possible distance. Consequently, theheat-exchange distance is established such that heat exchange isperformed over a portion of the comparatively long first capillary 153,that is, 500 to 1000 mm.

As a result, cooling the refrigerant in the first capillary 153 enhancesthe cooling effect of the refrigerating cycle 164 and provides bettercooling performance.

In addition, the refrigerant in the first evaporator 154 moves to thesecond evaporator 155 when the compressor 151 is stopped or themotor-operated valve 156 is closed. Because the liquid refrigerant beingmoved by a pressure difference cools the first capillary 153, thecooling effect of the refrigerating cycle 164 is enhanced, providingbetter cooling performance.

FIG. 19 schematically depicts the area in the vicinity of the firstevaporator 154.

As has already been depicted in FIG. 15 with reference to the secondembodiment, the freezer compartment 162 is located below therefrigerator compartment 163, and the first evaporator 154 is disposeddeep inside the refrigerator compartment 163 and above the secondevaporator 155.

The first capillary 153 and the second capillary 157 are connected atthe flow-dividing portion 158, providing a connection to themotor-operated valve 156. The motor-operated valve 156 is located abovethe first evaporator 154, in a void space across from the firstmotor-operated fan 165.

A connection is established between the motor-operated valve 156 and theinlet line of the first evaporator 154, and a linear structure is formedaccording to a pass pattern in which a plurality of tube runs aresequentially arranged in a single direction from the top of theevaporator downward. A connection is also established between the outletline of the first evaporator 154 and the second evaporator 155 via theflow-merging portion 159.

The evaporators are thus devoid of liquid traps, and the refrigerantpresent in the first evaporator 154 is smoothly transported to thesecond evaporator 155 by the pressure difference and gravity when aswitchover is made by the opening or closing of the motor-operated valve156 from a circuit that passes through the first evaporator 154 forrefrigeration cooling to a circuit that creates a bypass through thesecond evaporator 155 for freezer cooling.

The efficiency of the refrigerating cycle 164 can therefore be enhancedby avoiding a situation in which a significant gas deficit is producedin the second evaporator 155 for freezer cooling during the switching ofthe motor-operated valve 156 and the amount of sealed refrigerant mustbe increased.

In addition, abnormal frosting can be prevented because themotor-operated valve 156 is positioned, in relation to the firstevaporator 154, on the downstream side of the air flow created by thefirst motor-operated fan 165.

FIG. 20 schematically depicts a modification of the first evaporator154.

As shown in FIG. 20, neighboring tube runs in the first evaporator 154(fin-coil type) underneath the first motor-operated fan 165 are shiftedfrom each other by a pitch 175 to form a staggered layout in accordancewith a pass pattern in which the tube runs are sequentially arranged ina single direction from the top of the evaporator downward, allowing theline to occupy a wider projected area in a cross section perpendicularto the direction of air flow without forming liquid traps in the firstevaporator 154. In addition, the heat-transfer coefficient can beincreased by the enhanced turbulence in the line, and the efficiency ofthe cooling system can be raised.

FIG. 21 schematically depicts another modification of the arrangement ofFIG. 19.

As shown in FIG. 21, the flow-dividing portion 158, the second capillary157, and the flow-merging portion 159 are disposed in the refrigeratorcompartment 163, and the flow-merging portion 159 is placed in thevicinity of the outlet line of the first evaporator 154.

With this arrangement, the number of welded connections in the freezercompartment 162 is thus minimized (reduced to two) by employing a simplestructure in which the second evaporator 155 is merely connected withthe inlet and outlet lines.

Work is thus facilitated at the comparatively inaccessible secondevaporator 155 below the first evaporator 154.

In addition, if the first evaporator 154, motor-operated valve 156,second capillary 157, flow-dividing portion 158, and flow-mergingportion 159 are integrated into a single unit, this sub-assembled unitcan be incorporated into the system itself merely by performing weldingat two locations. It is also possible to cut down on labor and toimprove welding reliability.

FIG. 22 depicts a fifth embodiment of a bottom-freezer refrigeratoraccording to the present invention.

The refrigerator shown in FIG. 22 includes a refrigerator body 150having at least one freezer compartment 162, at least one refrigeratorcompartment 163 provided above the freezer compartment 162, and amachine chamber 169 provided at a bottom portion of the back surface ofthe freezer compartment 162. A first evaporator 154 and a motor-operatedfan 165 serving as a first cold air circulation means are mounted on theback surface of the refrigerator compartment 163. A motor-operated valve156 serving as a channel control means is provided above the firstevaporator 154, and a motor-operated fan 167 (second cold aircirculation means) and a second evaporator 155 are mounted on the backsurface of the freezer compartment 162 above the machine chamber 169.

Because the second evaporator 155 is positioned below the firstevaporator 154, the refrigerant or the machine oil inside the firstevaporator 154 gradually returns to the second evaporator 155 in thedirection of gravity when the supply of refrigerant to the firstevaporator 154 is stopped by the switching of the motor-operated valve156. A smooth return of the refrigerant is thus facilitated, and it isunlikely that the refrigerant stays in the first evaporator 154,preventing the cooling performance or reliability from being adverselyaffected while avoiding situations in which the system operates with ashortage of the refrigerant or machine oil.

FIG. 23 depicts a sixth embodiment of a bottom-freezer refrigeratoraccording to the present invention.

As shown in FIG. 23, a first evaporator 154 and a first motor-operatedfan 165 are mounted on the back surface of a refrigerator compartment163, while a second evaporator 155 and a second motor-operated fan 167are mounted on a bottom portion of a freezer compartment 162 in front ofa machine chamber 169.

With this arrangement, the interior of the freezer compartment 162 canbe used freely as a storage space, and the difficult-to-use portion ofthe bottom of the refrigerator body 150 can be used as a space foraccommodating the machine chamber 169 and the second evaporator 155,making it possible to configure the inactive capacity in a moreefficient manner.

In the case of a drawer-type freezer compartment, the bottom can be madeflat all the way to the back surface, increasing the usable internalcapacity in practical terms.

Although the present invention has been fully described by way ofexamples with reference to the accompanying drawings, it is to be notedhere that various changes and modifications will be apparent to thoseskilled in the art. Therefore, unless such changes and modificationsotherwise depart from the spirit and scope of the present invention,they should be construed as being included therein.

What is claimed is:
 1. A refrigerator having a refrigerator compartment(102) and a freezer compartment (103) both defined therein, saidrefrigerator compartment (102) having a low-temperature storage chamber(133) of a temperature lower than that of said refrigerator compartment(102), said refrigerator comprising: a compressor (111), a condenser(112), a first throttling device (113), a channel control valve (122), arefrigerator cooling unit (110), and a freezer cooling unit (108)connected in series to form a refrigerating cycle, said refrigeratorcooling unit (110) and said freezer cooling unit (108) beingaccommodated in said refrigerator compartment (102) and said freezercompartment (103), respectively; a second throttling device (124)connected in parallel with said refrigerator cooling unit (110); a firstair fan (109) for sending cold air heat-exchanged by said refrigeratorcooling unit (110) to said refrigerator compartment (102); a second airfan (107) for sending cold air heat-exchanged by said freezer coolingunit (108) to said freezer compartment (103); a suction duct (115) forintroducing air inside said refrigerator compartment (102) to saidrefrigerator cooling unit (110); a discharge duct (116) for introducingair cooled by said refrigerator cooling unit (110) into saidrefrigerator compartment (102) and into said low-temperature storagechamber (133); and an electrically-operated damper (140) accommodated insaid discharge duet, wherein when said electrically-operated damper(140) is opened, an amount of air to be introduced into saidlow-temperature storage chamber (133) is greater than an amount of airto be introduced into said refrigerator compartment (102).
 2. Therefrigerator according to claim 1, wherein said first air fan (109) hasa varying capacity and can be operated at one of a first speed and asecond speed higher than the first speed, and wherein when saidlow-temperature storage chamber (133) is cooled, said first air fan(109) is operated at the first speed.
 3. The refrigerator according toclaims 1, wherein said compressor (111) has a varying capacity and canbe operated at one of a first speed and a second speed higher than thefirst speed, and wherein when said low-temperature storage chamber (133)is cooled, said compressor (111) is operated at the second speed.
 4. Therefrigerator according to claim 1, further comprising a timer, a firsttemperature detector (51) for detecting a temperature within saidrefrigerator compartment (102), and a second temperature detector (52)for detecting a temperature within said low-temperature storage chamber(133), wherein when a temperature detected by said first temperaturedetector (51) is higher than a set temperature of said refrigeratorcompartment (102) and when a temperature detected by said secondtemperature detector (52) is higher than a set temperature of saidlow-temperature storage chamber (133), operation of said first air fan(109) is started, and said electrically-operated damper (140) is openedafter a lapse of time recorded by said timer.
 5. The refrigeratoraccording to claim 1, further comprising a timer, a first temperaturedetector (51) for detecting a temperature within said refrigeratorcompartment (102), and a second temperature detector (52) for detectinga temperature within said low-temperature storage chamber (133), whereinwhen a temperature detected by said first temperature detector (51)becomes lower than a set temperature of said refrigerator compartment(102) and when a temperature detected by said second temperaturedetector (52) becomes lower than a set temperature of saidlow-temperature storage chamber (133), said channel control valve (122)is closed and operation of said first air fan (109) is stopped after alapse of time recorded by said timer.
 6. The refrigerator according toclaim 1, wherein said channel control valve (122) is openedsimultaneously with a stop of said compressor (111), and said first airfan (109) is operated for a predetermined period of time.
 7. Therefrigerator according to claim 1, further comprising a firsttemperature detector (51) for detecting a temperature within saidrefrigerator compartment (102), and a second temperature detector (52)for detecting a temperature within said low-temperature storage chamber(133), wherein when a temperature detected by said first temperaturedetector (51) is higher than a set temperature of said refrigeratorcompartment (102) and when a temperature detected by said secondtemperature detector (52) is higher than a set temperature of saidlow-temperature storage chamber (133), said channel control valve (122)is opened and operation of said first air fan (109) is started after alapse of predetermined time.
 8. The refrigerator according to claim 1,further comprising a heater (142) accommodated in said discharge duct(116), a first temperature detector (51) for detecting a temperaturewithin said refrigerator compartment (102), and a second temperaturedetector (52) for detecting a temperature within said low-temperaturestorage chamber (133), wherein when a temperature detected by said firsttemperature detector (51) becomes a set temperature of said refrigeratorcompartment (102) before a temperature detected by said secondtemperature detector (52) becomes a set temperature of saidlow-temperature storage chamber (133), said heater (142) is suppliedwith electricity.
 9. The refrigerator according to claim 1, furthercomprising a plurality of illumination lamps (141) accommodated in saiddischarge duct (116), a first temperature detector (51) for detecting atemperature within said refrigerator compartment (102), and a secondtemperature detector (52) for detecting a temperature within saidlow-temperature storage chamber (133), wherein when a temperaturedetected by said first temperature detector (51) becomes a settemperature of said refrigerator compartment (102) before a temperaturedetected by said second temperature detector (52) becomes a settemperature of said low-temperature storage chamber (133), saidplurality of illumination lamps (141) are supplied with electricity. 10.A refrigerator having a refrigerator compartment (163) and a freezercompartment (162); both defined therein, said refrigerator comprising: acompressor (151), a condenser (152), a first pressure reduction means(113); (153), a channel control valve (156), a first evaporator (154),and a second evaporator (155) connected in series to form arefrigerating cycle (164), said channel control valve (156) beingpositioned within a refrigerator duct formed in said refrigeratorcompartment (163), said first and second evaporators (154, 155) beingaccommodated in said refrigerator compartment (153) and said freezercompartment (162), respectively; a bypass conduit having a secondpressure reduction means (157) for connecting a flow-dividing portion(158) positioned between said first pressure reduction means (153) andsaid channel control valve (156), and a flow-merging portion (159)positioned between said first evaporator (154) and said secondevaporator (155); a first cold air circulation means (165) accommodatedin said refrigerator compartment (163) for circulating an internal airof said refrigerator compartment (163); and a second cold aircirculation means (167) accommodated in said freezer compartment (162)for circulating an internal air of said freezer compartment (162),wherein a pressure reduction of said first pressure reduction means(153) is greater than that of said second pressure reduction means(153).
 11. The refrigerator according to claim 10, wherein heat isexchanged between a pipe (171) connecting said second evaporator (155)and said compressor (151), and said first pressure reduction means(153).
 12. The refrigerator according to claims 10, wherein heat isexchanged between said first pressure reduction means (153) and a pipe(173) connecting said first evaporator (154) and said second evaporator(155).
 13. The refrigerator according to claim 10, wherein said freezercompartment (162) is positioned below said refrigerator compartment(163), said first evaporator (154) being disposed above said secondevaporator (155) and having a pass pattern in which a plurality of tuberuns are sequentially arranged in a single direction from top of saidfirst evaporator (154) downward.
 14. The refrigerator according to claim13, wherein said first evaporator (154) is of a fin-coil-type onedisposed near said first cold air circulation means (165) and has aplurality of tube runs, of which neighboring tube runs are shifted fromeach other by a predetermined pitch (175) to form a staggered layout.15. The refrigerator according to claim 10, wherein said flow-dividingportion (158), said second pressure reduction means (157), and saidflow-merging portion (159) are disposed in said refrigerator compartment(163).
 16. A refrigerator having a refrigerator compartment (102; 163),a freezer compartment (162), and a machine chamber (169) all definedtherein, said refrigerator compartment (163) being formed above saidfreezer compartment (162), said machine chamber (169) being formed at alower portion of said freezer compartment (162), said refrigeratorcomprising: a first cold air circulation means (165) and a firstevaporator (154) both located on a surface deep inside said refrigeratorcompartment (163); a channel control valve (156) positioned within arefrigerator duct formed in said refrigerator compartment (163); and asecond cold air circulation means and a second evaporator (155) bothlocated on a surface deep inside said freezer compartment (162), saidsecond evaporator (155) being disposed below said first evaporator(154).
 17. The refrigerator according to claim 16, wherein said channelcontrol valve (156) is disposed downstream of said first evaporator(154) with respect to a direction of flow of an internal air of saidrefrigerator compartment (163).
 18. The refrigerator according to claim16, wherein said channel control valve (156) is disposed adjacent saidfirst cold air circulation means (165).
 19. A refrigerator having arefrigerator compartment (163), a freezer compartment (162), and amachine chamber (169) all defined therein, said refrigerator compartment(163) being formed above said freezer compartment (162), said machinechamber (169) being formed at a lower portion of said freezercompartment (162), said refrigerator comprising: a first cold aircirculating means (165) and a first evaporator (154) both located on asurface deep inside said refrigerator compartment (163); and a secondcold air circulating means and a second evaporator (155) both located atanother lower portion of said freezer compartment (162) in front of saidmachine chamber (169).